1. Field of the Invention
The present invention relates to a magnetic recording medium in which a recording layer is formed in a predetermined concavo-convex pattern and recording elements are each formed as a convex portion of the concavo-convex pattern. The present invention also relates to a magnetic recording and reproducing apparatus provided with such a magnetic recording medium and a method for manufacturing the magnetic recording medium.
2. Description of the Related Art
A significant improvement in the areal density of conventional magnetic recording media such as hard disks has been achieved by, for example, reducing the size of magnetic particles constituting a recording layer, changing materials, and improving the precision of head processing. A further improvement in the areal density is expected in the future. However, problems due to limitations with respect to head processing technology and the broadening of the magnetic field from a magnetic head have become apparent, resulting in issues such as incorrect recording of information on a track adjoining a target recording track and crosstalk during reproduction. The improvement of the areal density by conventional improvement techniques has therefore reached its limit.
Hence, discrete track media and patterned media have been proposed as candidates for magnetic recording media in which a further improvement in the areal density can be achieved (see, for example, Japanese Patent Application Laid-Open No. H09-97419). In the discrete track media and patterned media, a recording layer in a data area is formed in a concavo-convex pattern, and recording elements are each formed as a convex portion of the concavo-convex pattern.
In order to obtain excellent recording-reproducing characteristics, it is considered that, preferably, the flying height of a magnetic head is kept constant so that the magnetic gap between the magnetic head and the upper surface of each recording element is held constant. Hence, it has been proposed to flatten the surface of a magnetic recording medium by filling concave portions between recording elements with a filling material such as a non-magnetic material.
However, in a disk-shaped magnetic recording medium such as a hard disk, the circumferential speed of the medium relative to a magnetic head is lower on the radially inner side and is higher on the radially outer side. When the outer diameter of a magnetic recording medium is relatively large or when the rotation speed thereof is relatively high, the relative speed between the magnetic recording medium and a magnetic head can be extremely large in the radially outer area of the magnetic recording medium. Hence, even when the surface of the magnetic recording medium is flat, the flying height of the magnetic head can be larger in the radially outer area of the magnetic recording medium than in other areas. Therefore, the recording-reproducing characteristics may deteriorate.
In addition, a technique is known in which a magnetic head is urged toward a magnetic recording medium by the utilization of negative pressure. However, when the relative speed between a magnetic recording medium and a magnetic head is extremely high, an increase in the flying height of the magnetic head may not be suppressed sufficiently in the radially outer area of the magnetic recording medium even when the technique for urging the magnetic head toward the magnetic recording medium utilizing negative pressure is used.